The present invention relates to adjustable pliers, and more particularly to a self-adjusting parallel jaw pliers.
Parallel jaw adjustable pliers are popular because of their utility in being able to securely hold variously-sized workpieces. The pliers generally provide for adjustability with a slip joint connecting one of the jaw/handle members to the other. However, a continuing problem has been providing for easy adjustment of the jaw spacing so as to permit single hand operation of the pliers.
Prior art pliers have tried to provide single hand operation by using a spring to bias the jaws away from each other. See, e.g. U.S. Pat. Nos. 5,660,089 to Chow 4,429,460 to Hill et al. This arrangement proves difficult to use with a single hand when the jaws are opened more widely than that needed for optimal gripping of the workpiece, and a second hand is required to move the jaws toward each other against the force of the spring. As can be readily appreciated, pliers that were intended to permit single hand operation are likely require two hands to properly space the jaw members for gripping the workpiece.
Accordingly, it is the principle art object of the present invention to provide and improve adjustable pliers.
More specifically, it is an object to the present invention to provide a parallel-jaw adjustable pliers that is adapted for single-hand operation.
It is a further object to provide a parallel-jaw adjustable pliers that automatically sizes the spacing between the jaws to accommodate the workpiece being grasped.